A recent vehicle is mounted with a vehicle steering device that uses a motor to apply an assist force for a driver steering the steering wheel. If such a vehicle steering device is applied to a vehicle having a large axle weight, such as a large car, a larger steering force is required as compared to that for a small vehicle having a small axle weight, such as a small car. Then, a larger force is required to assist the steering.
To accommodate these cases, for example, the Japanese Patent Application Publication No. 2004-142622 discloses a steering device having two motors, two steering torque sensors, and two ECUs that perform driving control of the two motors, respectively.
More specifically, in the steering device according to the Japanese Patent Application Publication No. 2004-142622, a steering wheel, column unit, an intermediate transmission unit and a gearbox unit are connected in this order. The column unit and the gearbox unit are respectively provided with a first and second motors that apply assist forces for steering, and a first and second torque sensors that detect the torque applied to the steering shaft. The first and second motors are respectively connected with a first and second ECUs that provide motor driving signals to the motors.
The steering device according to the Japanese Patent Application Publication No. 2004-142622 allows for improving workability and mountability when attaching the gearbox unit to the vehicle body, as well as for improving operation feeling of the operator.